Self-cleaning screen



June 3, 1930. e. A. TURNER SELF CLEANING SQREE N Filed July 28, 1926 61A. Turner ATTORNEY Patented June 3-, 1930 if I PATENT OFFICE.

' GEORGE A. TURNER, F STOCKTON, CALIFORNIA SELF-CLEANING SCREEN Application filed July 28, 1926. Serial No. 125,357.

This invention relates to improvements in as must now be done to avoid an appreciable l the shaker screens used in cleaning and grading grains and seeds of all kinds.

Such screens whether of wire mesh or of 5 plates having orifices or slots, always of course have transverse cross members or webs inherent in their construction, to form either the cross strands of the mesh or the connecting means between any series of openings or slots. hen acting on certain kinds of produce these cross members tend to catch husks, pods, or other foreign matter and prevent the same from being effectively distributed from the screen, as is well known to those opcrating such devices. Sooner or later therefore the screen becomes choked up, preventing the same from operating to capacity. Screening work must then be stopped at intervals to enable the screen to be cleared of the matter accumulated thereon. Various methods are used to effect this cleaning operation, none of which. are entirelysatisfactory and detract from the output of the screen owing to the loss of time incident to cleaning operations as well as the partial choking up of the screen had before it is cleaned. Unless the screen is so cleaned howi ever the capacity of the same is materially reduced, and in some instances instead of resorting to the above described cleaning operations a number of screens'is used to maintain the output at a level which could be maintained by a single screen if the latter were prevented from clogging up.

The principal object of my invention therefore is to eliminate the above defects in shaker screen construction by forming the screen in such a manner that while the necessary cross members are still present, such members are so disposed as to be out of the way of any matter passing down the screen, so that they do not offer any interference with the free longitudinal and downward movement of all such matter on the screen.

Further objects of my invention are to construct the screen so that the screeningopenings are practically continuous from endto end and sothat the screen becomes automatically reinforced against transverse sagging,

5 Without having to use screens of small size,

sag ofthe screen.

A further object of the invention is to produce a simple and inexpensive device and yet one which will be exceedingly effectivefor the purpose for which it is designed.

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of'the following specification and claims.

In the drawings similar-characters of reference indicate corresponding parts in the several views:

Fig. 1 is a fragmentary longitudinal section of my improved screen construction.

, Fig. 2 is a fragmentary perspective View of the screen.

Fig. 3 is a fragmentary top plan View of the screen.

, Referring now more particularly tothe characters of reference on the drawings, the numeral 1 denotes a suitable frame in which the screen is mounted. The frame as usual is arranged to be supported so that it may be shaken or reciprocated longitudinally, but inasmuch as such arrangements are common and well known it is not thought necessary to illustrate or describe the same here. The screen itself comprises a plate 2 mounted in and extending from end to end of the frame 1. This plate is provided throughout its extent with rows of longitudinally extendingand transversely spaced and alined slots 3, the length and width of said slots depending of course upon the nature and size ofthe material to be handled. The slots of each row being transversely alined a single cross web 4 is formed in the plate between each such row. Ordinarily with astraight plate this web (which forms the rear ends of one row of slots and the forward ends of the adjacent row) therefore is directly in the path of all matter moving down the screen with the shaking movement, and catching against certain forms of such matter prevents'the free discharge of the same from the lower end of the screen. 1

I'therefore avoid this interference of the member from its forward to its rear end. The substantially vertical offset portions which join the different steps as shown at 5 extend from adjacent but ahead of the rear ends of the slots to adjacent but ahead of the forward ends of the successive rows of slots on the step below. Since the slots are fairly close together longitudinally the Webs connecting the same are short and the step connection members are correspondingly short. There is therefore no very great drop from one step onto another.

By means of this construction the connecting webs l are not in the longitudinal plane of travel of the matter on the screen but are located mainly in the vertical step connecting portions 5, so that they *annot engage or interfere with matter moving along the screen.

The frame 1 is set at such an angle that the various step surfaces of the plate 2 have a slight downward slant from front to rear as shown in Fig. 1, so that the matter on the screen will not tend to pile up against the offset portions 5. The screen is therefore absolutely self-clearing and screening operations can be carried out continuously without ever having to halt the operation of the screen to clear the same of foreign matter manually or otherwise. The portions 5 also preferably have a forward slope from top to bottom, so that the slots in the operating surface of the plate are practically continuous from end to end. Such a plate therefore as will be evident hasa greater slotted area and consequently a considerably greater screening capacity than one of the same length as ordinarily constructed.

As will be noted, the members 5, being practically in a plane at right angles to the screening surface of the plate 2, also form transverse ribs which effectively reenforce the plate, and preventthe same from sagging transversely, as is commonly the case with screens as ordinarily constructed.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

lVhile this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claim.

Having thus described my invention what I claim as newand useful and desire to secure by Letters Patent is:

A screen comprising a plate arranged as a plurality of successively descending steps with connecting webs therebetween; each stop being provided with longitudinal slots longitudinally alined with those of adjacent steps and extending from adjacent the base of the web of thestep above, to and partially down the web at the opposite end of the step,

the webs being disposed at an angle to the steps and to a vertical plane such that the forward ends of the slots of one step are disposed in a vertical plane beyond the adjacent ends of the slots of the adjacent step below, such slots at' said ends being the same width as the ends of the slots above.

In testimony whereof I afiix my signature.

GEORGE A. TURNER. 

